pm_trans_check

Synopsis

Interface Level

Solaris DDI specific (Solaris DDI)

Parameters

datap

Pointer to a pm_trans_data structure

intervalp

Pointer to time difference when next power cycle will be advised

Description

The pm_trans_check() function checks if a power-cycle is currently advised based on
data in the pm_trans_data structure. This function is provided to prevent
damage to devices from excess power cycles; drivers for devices that are
sensitive to the number of power cycles should call pm_trans_check() from their power(9E)
function before powering-off a device. If pm_trans_check() indicates that the device should not
be power cycled, the driver should not attempt to power cycle the
device and should fail the call to power(9E) entry point.

If pm_trans_check() returns that it is not advised to power cycle the
device, it attempts to calculate when the next power cycle is
advised, based on the supplied parameters. In such case, intervalp returns the
time difference (in seconds) from the current time to when the next power
cycle is advised. If the time for the next power cycle cannot
be determined, intervalp indicates 0.

To avoid excessive calls to the power(9E) entry point during a period
when power cycling is not advised, the driver should mark the corresponding
device component busy for the intervalp time period (if interval is not
0). Conveniently, the driver can utilize the fact that calls to pm_busy_component(9F)
are stacked. If power cycling is not advised, the driver can call
pm_busy_component(9F) and issue a timeout(9F) for the intervalp time. The timeout()
handler can issue the corresponding pm_idle_component(9F) call.

The format field of pm_trans_data accepts either DC_SCSI_FORMAT or DC_SMART_FORMAT. If the
caller provides information from a SCSI Log Page, it should set the
format field to DC_SCSI_FORMAT, and provide valid data in svc_date[], lifemax,
ncycles and flag in the pm_scsi_cycles structure. If the caller provides information
from a SMART feature attribute, it should set the format field to DC_SMART_FORMAT
and provide valid data in allowed, usedup and flag in the pm_smart_count
structure, where allowed indicates the normalized cycle count before reaching the borderline threshold
cycle count, and usedup indicates the normalized consumed cycle count.

The flag field in both pm_scsi_cycles and pm_smart_count structures is reserved for
future use and must be set to 0.